In any metropolitan region, the articulation between metropolitan scale of issues and the multiplicity of government jurisdictions poses a challenge for the implementation of environmental policies. Focused on the Buenos Aires Metropolitan Region, this article examines the coordination of metropolitan environmental policies in a federal context. The first part describes the metropolitan region and its main environmental problems, the way in which Argentine federalism assigns environmental competences to the different government levels and the mechanisms it sets for metropolitan governance, and the characteristics and flaws of the inter-jurisdictional organizations at work in the metropolitan region. The second part discusses the factors explaining those flaws. It argues that the shortcomings of the metropolitan coordination of environmental policies are explained by the interaction between federal institutions and other political system variables such as the dynamics of party-electoral accumulation, the setting of government agendas, the role of state bureaucracies, and the impact of environmental activism.